The handle bar end of a threadless MTB stem cut off.
I had a few and tried it out one day and wow it fit. Going to use another one for the foot brake mount on that bike.could have welded or drilled the frame but couldn't make up my mind on location.

Here's one that I did a few years ago. It's not a custom shifter but it looks real kewl... It's a old 5-speed Sting Ray shifter mounted like a 'jockey' shift on a custom 1950 Schwinn 5-speed cruiser.
I took these pics a little early before the bike was finished. :roll:

Somewhat primitive in design, but with the "idiot proof" theory applied. This is now 6 years old, and still works just like it should. One up close shot, one from far enough away to see the shift lever. Can you say "suicide?"

Not as nice as some of the more machined pieces that have come along in the last few years, but I did what's here with what I had on hand at the time. I don't have any welding equipment so it is a bolt-on piece.

not sure if any pictures on this thread include this.....but a lot of these i've seen include chrome/metal housings just off the shift that allow for a quick and sharp bend. The closest thing ive found online are brake cable noodles. Is that what these are or am i missing the right name?